如何在WPF Canvas上繪製網格線？

Question

我需要建立在WPF在畫布上繪製功能網格線：

void DrawGridLine(double startX, double startY, double stepX, double stepY, 
        double slop, double width, double height) 
{ 
    // How to implement draw gridline here? 
} 

我怎麼會去嗎？

Answer 1

你並不需要用WPF「畫」任何東西。如果要繪製線條，請使用適當的幾何圖形繪製線條。

在你的情況下，它可能很簡單。你只是繪製一個網格，所以你可以創建一個DrawingBrush來繪製一個單一的網格正方形，並將其平鋪以填充其餘部分。要繪製您的圖塊，您可以將其視爲繪製X的。所以有一個20x10瓦（相當於stepX和stepY）：

（PS，斜率slop是多餘的，因爲你已經擁有水平和垂直步長）

<DrawingBrush x:Key="GridTile" Stretch="None" TileMode="Tile" 
       Viewport="0,0 20,10" ViewportUnits="Absolute"> 
        <!-- ^^^^^^^^^^^ set the size of the tile--> 
    <DrawingBrush.Drawing> 
     <GeometryDrawing> 
      <GeometryDrawing.Geometry> 
       <!-- draw a single X --> 
       <GeometryGroup> 
        <!-- top-left to bottom-right --> 
        <LineGeometry StartPoint="0,0" EndPoint="20,10" /> 

        <!-- bottom-left to top-right --> 
        <LineGeometry StartPoint="0,10" EndPoint="20,0" /> 
       </GeometryGroup> 
      </GeometryDrawing.Geometry> 
      <GeometryDrawing.Pen> 
       <!-- set color and thickness of lines --> 
       <Pen Thickness="1" Brush="Black" /> 
      </GeometryDrawing.Pen> 
     </GeometryDrawing> 
    </DrawingBrush.Drawing> 
</DrawingBrush> 

這需要繪圖的護理線。現在爲了能夠從邊緣繪製它們在網格中的偏移量，您需要使用另一個畫筆繪製具有所需尺寸的矩形，並用瓦片填充。所以有(30, 45)（對應於startX和startY）與width和height起始位置，130x120：

<DrawingBrush x:Key="OffsetGrid" Stretch="None" AlignmentX="Left" AlignmentY="Top"> 
    <DrawingBrush.Transform> 
     <!-- set the left and top offsets --> 
     <TranslateTransform X="30" Y="45" /> 
    </DrawingBrush.Transform> 
    <DrawingBrush.Drawing> 
     <GeometryDrawing Brush="{StaticResource GridTile}" > 
      <GeometryDrawing.Geometry> 
       <!-- set the width and height filled with the tile from the origin --> 
       <RectangleGeometry Rect="0,0 130,120" /> 
      </GeometryDrawing.Geometry> 
     </GeometryDrawing> 
    </DrawingBrush.Drawing> 
</DrawingBrush> 

後來終於用它，只是把它設置爲網格的背景（或其他面板） ：

<Grid Background="{StaticResource OffsetGrid}"> 
    <!-- ... --> 
</Grid> 

下面是它的最終看起來像：

---

如果要動態地生成刷，這裏的基於上述XAML等效功能：

static Brush CreateGridBrush(Rect bounds, Size tileSize) 
{ 
    var gridColor = Brushes.Black; 
    var gridThickness = 1.0; 
    var tileRect = new Rect(tileSize); 

    var gridTile = new DrawingBrush 
    { 
     Stretch = Stretch.None, 
     TileMode = TileMode.Tile, 
     Viewport = tileRect, 
     ViewportUnits = BrushMappingMode.Absolute, 
     Drawing = new GeometryDrawing 
     { 
      Pen = new Pen(gridColor, gridThickness), 
      Geometry = new GeometryGroup 
      { 
       Children = new GeometryCollection 
       { 
        new LineGeometry(tileRect.TopLeft, tileRect.BottomRight), 
        new LineGeometry(tileRect.BottomLeft, tileRect.TopRight) 
       } 
      } 
     } 
    }; 

    var offsetGrid = new DrawingBrush 
    { 
     Stretch = Stretch.None, 
     AlignmentX = AlignmentX.Left, 
     AlignmentY = AlignmentY.Top, 
     Transform = new TranslateTransform(bounds.Left, bounds.Top), 
     Drawing = new GeometryDrawing 
     { 
      Geometry = new RectangleGeometry(new Rect(bounds.Size)), 
      Brush = gridTile 
     } 
    }; 

    return offsetGrid; 
}